1. Field of the Invention
The present invention relates to a method for using a molding. More particularly, it pertains to a method for using a molding excellent in chemical, solvent, chloroflurocarbon and hydrochlorofluorocarbon resistances.
2. Description of Related Art
Since trichloromonofluoromethane (CFC11) which is widely used for thermal insulation foam of refrigerators threatens destruction of the ozone layer, it is intended worldwide to be replaced with 1,1-dichloro-2,2,2-trifluoroethane (HCFC 123) or 1,1-dichloro-1-fluoroethane (HCFC 141b) at the present time. However, the aforementioned HCFC 123 and HCFC 141b have each higher solubilities for various resins than those of the previous chlorofluorocarbon such as CFC 11. Accordingly, acrylonitrile/butadiene/styrene (ABS) resin and high impact resistant polystyrene (HIPS) that are generally used for the inner liner of a refrigerator at present can not withstand the combined use with polyurethanes containing HCFC 123 or HCFC 141b in direct contact therewith.
Moreover as the environmental preservation problem, the proceeding of recovery and reuse of waste plastics has recently become the worldwide subject for a future study.
Under such circumstances, there are proposed an ABS resin with a high content of acrylonitrile (Japanese Patent Application Laid-Open No. 284906/1990) and a polyolefinic resin composition (Japanese Patent Application Laid-Open No. 209240/1986) as a material to be used for the inner liner of a refirgerator which is resistant against chlorofluorocarbons and hydrochlorofluorocarbons.
Although somewhat improved in the resistance against such (hydro)chlorofluorocarbons, the above-mentioned ABS resin is not sufficiently improved in the resistance; besides the use of excess acrylonitrile in ABS resin to be used as a refrigerator member causes unfavorable odor as well as a working environmental problem in that the acrylonitrile is liberated from the ABS resin at the time of heating for recovery.
On the other hand, since the aforesaid polyolefinic resin composition is used in the form of a mixture with a resin other than a styrenic resin, for example, by being compounded with an acrylic polymer for the main purpose of improving the adhesivity to the polyurethane foam, the use of the composition is greatly limited in the case of recovery and reuse thereof.
In addition, there is proposed a multi-layer structure of a polyolefinic resin and other resin (Japanese Patent Application Laid-Open No. 28240/1987), but the difficulty in recovery and reuse thereof is not improved at all as compared with that of the above-mentioned mixture of the composition.
In view of the aforestated circumstances facing such difficulty, intensive research and investigation were concentrated by the present inventors on the development of a molding which is easy in recovery and reuse, usable in a chlorofluorohydrocarbon atmosphere and resistant to alternative (hydro)chlorofluorocarbons by adopting syndiotactic polystyrene excellent in chemical and solvent resistances as the material for the inner liner of a refrigerator.
As a result it has been discovered that the sheet for thermoforing comprising as the primary ingredient a syndiotactic polystyrene having a high degree of syndiotactic configuration, a weight-average molecular weight of at least 100,000 and a crystallinity within a definite range, and laminate containing at least one layer comprising such syndiotactic configuration as the primary ingredient are effective as the raw material for the molding and also that the molding made of the aforesaid sheet for thermoforming or the laminate by means of thermoforming is well suited for attaining the purpose of the development. The present invention has been accomplished on the basis of the abovedescribed finding and information.